Speaking at a press conference in London, Ayelet Svatitzky, whose brother was killed in a raid on his kibbutz in southern Israel, said her "life stopped" on 7 October.

Her other brother and mother have both been taken hostage by Hamas militants.

"I try not to deal with the loss of my brother because I find it too painful and if I start thinking about that too much it would hurt too much, and it would break me - and I don't have the privilege of breaking," she said.

"Because I have a mission - I need to be efficient, effective and productive trying to get the Red Cross to family members to see them, to get lists of who has been taken.

"We are chasing information, we are trying to get the hostages help and to get information out."

Ofri Bibas Levi's brother was taken with his wife and two children.

"It is like living in a nightmare," she said.

"The pictures keep running in front of my eyes. I feel guilty for eating, I feel guilty for sleeping in my own bed, I feel guilty for playing with my own children.

Talking about the recent release of some of the hostages, she said: "It is psychological torture, hearing that they are releasing this one, or this one.

"We want all of them back, and we want all of them back now together."

David Barr's sister-in-law was shot dead in her kibbutz in southern Israel during the attack.

He said: "It took four days to identify what we call the 'Smile of the south of Israel'.

"She was well-known - she worked as a dental assistant and in the past few years, also, a keep-perfect freak. She simply went for a run in her kibbutz.

"She was shot in the back and shot again in the head at point-blank range.

"Life is turned upside down by death, by hatred, by evil people, monsters."

Downing Street said on Tuesday that at least 12 British nationals are known to have died either in or since the 7 October attack - with five people still missing.

Among the dead are two teenagers, a soldier, people visiting Israel on holiday, and a music festival security guard.

Hamas released two Israeli hostages on Monday night, after releasing two US citizens on Friday.

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Israel-Hamas war - latest updates

On Monday, before the release of the two Israeli hostages, a spokesperson for the Israel Defence Forces (IDF) said 222 people were being held hostage in Gaza.

According to the Hamas-run Gaza health ministry, at least 5,100 Palestinians have been killed in the Gaza Strip since Israel launched retaliatory air strikes in response to Hamas's attack on Israel on 7 October.

At least 1,400 Israelis were killed in that attack, according to Israeli officials.